seo(site): ship comparison, vs-termux, claude-code-android pages + internal links

3 long-tail pages targeting 'opencode vs chatgpt/copilot', 'vs termux',
'claude code on android'. Added to sitemap, footer nav, in-content links
from landing + guide + troubleshooting. All have canonical + install CTAs.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs-site/index.html

@@ -280,6 +280,7 @@ footer a{margin:0 8px}
       <li><b>Session management</b><span>Browse, create, and resume coding sessions on your server.</span></li>
     </ul>
     <p style="margin-top:16px"><a href="features/">Full feature list and use cases →</a></p>
+    <p style="margin-top:8px">Comparing options? See <a href="comparison/">OpenCode Mobile vs. ChatGPT &amp; Copilot</a>, <a href="vs-termux/">OpenCode Mobile vs. Termux</a>, or how to <a href="claude-code-android/">run Claude Code on Android</a>.</p>
   </div>
 </section>
 
@@ -363,6 +364,9 @@ OPENCODE_SERVER_PASSWORD=yourpassword opencode serve --hostname 0.0.0.0 --port 4
       <a href="download/">Download</a>
       <a href="guide/">Setup guide</a>
       <a href="features/">Features</a>
+      <a href="comparison/">Comparison</a>
+      <a href="vs-termux/">vs Termux</a>
+      <a href="claude-code-android/">Claude Code on Android</a>
       <a href="troubleshooting/">Troubleshooting</a>
       <a href="https://github.com/dzianisv/opencode-mobile">GitHub</a>
       <a href="https://dzianisv.github.io/opencode-mobile/fdroid/repo">F-Droid repo</a>